Lymphoid System- Lecture 9/30/21

Question 1

Primary lymphoid organs

Answer 1

Thymus and bone marrow

Question 2

Secondary lymphoid organs (3)

Answer 2

MALT, lymph nodes, spleen

Question 3

Bone marrow

Answer 3

Provide a protective environment for the development of immune competent B cells

Question 4

Thymus

Answer 4

Provides a protective environment for the development of immunocompetent T-cells

Question 5

Epitheliaoreticular cells

Answer 5

Supports the thymocytes, contribute to the blood thymus barrier

Question 6

Hassall’s Corpsucles

Answer 6

Whorls of specialized epithelioreticular cells that reside in thymic medulla, poorly understood but appears to regulate T-cell development

Question 7

Uncapsulated lymphoid organs (3)

Answer 7

• Tonsils
• Peyer’s patch
• appendix

Question 8

Encapsulated lymphoid organs (2)

Answer 8

• Lymph nodes

- Spleen

Question 9

Germinal center

Answer 9

Part of lymphoid nodule where the B-cells live/proliferate

Question 10

Diffuse zone

Answer 10

Part of lymphoid that houses T-cells

Question 11

MALT

Answer 11

Mucosa associated lymphoid tissue

Question 12

Mucosa

Answer 12

Epithelia, surrounding connective tissue (lamina propria), muscle layer just deep to it

Question 13

Submucosa

Answer 13

Layers underneath muscularis mucosa

Question 14

Tonsil types

Answer 14

• Pharyngeal
• Palatine
• Lingual

Question 15

Characteristics of palatine (lingual) tonsils

Answer 15

SSNKE epithelium, deep crypts, palatine and lingual histologically indistinguishable

Question 16

Characteristics of pharyngeal tonsil

Answer 16

• Pseudostratified epithelia with no crypts

Question 17

Peyer’s patch

Answer 17

Lives in the mucosa/submucosa of small intestine epithelium , simple columnar epithelium

Question 18

M (microfold) cell

Answer 18

Specialized epithelia with basal invaginations and active pinocytosis to allow for maximal contact between immune cells and possible antigens

Question 19

Appendix

Answer 19

Nodules line in the mucosa

Question 20

Septa

Answer 20

In the thymus, separates the lobes of the thymus

Question 21

Blood thymus barrier

Answer 21

Any cell in thymus that recognizes and antigen is killed, so if any pathogen were to get in the cell that recognizes it would be killed

Question 22

Involuting thymus

Answer 22

Adult thymus, largely CT and Fat because inactive

Question 23

Appendix functions (4)

Answer 23

• Immune surveillance
• Vestigal
• Endocrine organ
• Reserve of gut flora

Question 24

Lymph node

Answer 24

• Range from 1mm -several CM
• Concentrated in neck, axilla and groin
• Filter lymph and expose antigen

Question 25

Medullary cord

Answer 25

Loose CT, with highly cellular content

Question 26

Medullary sinus

Answer 26

Venous channel running between cords, discontinuous endothelium, traversed by reticular fibers

Question 27

Splenic cords and sinuses

Answer 27

Similar to lymph node, have blood cells in both, sinuses are not traversed by reticular fibers

Question 28

Subcapsular sinus

Answer 28

Sinus that runs just under the capsule

Question 29

Trebeculum

Answer 29

CT that supports the lymph node

Question 30

High endothelial venules

Answer 30

Lymphocyte entry only, becomes leaky during cortical reaction

Question 31

Spleen functions (6)

Answer 31

- immune response - destroys damaged, senescent blood cells - Sequesters monocytes - Hematopoiesis - Storage of platelets - Recycling iron

Question 32

Red pulp

Answer 32

Where the splenic cords and splenic sinuses are

Question 33

White pulp

Answer 33

Contains the lymphatic double and the periarterial lymphatic sheath

Question 34

PALS

Answer 34

Periarterial lymphatic sheath, surrounds the central artery

Question 35

Trebecular artery

Answer 35

Surrounded by CT

Question 36

Red pulp cords

Answer 36

- Loose CT and reticular fibers, blood enters cords first

Question 37

Red pulp sinuses

Answer 37

- Venous channels lined by elongated discontinuous endothelial cells

Question 38

Marginal zone

Answer 38

First place that RBCs encounter WBCs of the red pulp cord